A disk drive unit includes a stationary body; a rotating body rotatably supported on the stationary body, a seal part configured to form a first gas-liquid interface of a lubricant existing in a gap between the stationary body and the rotating body, and a groove-shaped opening opposing the seal part and communicating to the gap via a communication hole. The seal part has a shape such that the gap gradually increases towards an aperture opposing the groove-shaped opening, and the groove-shaped opening has a shape such that the gap gradually increases towards an aperture opposing the seal part.